Highly Sensitive and Robust Polysaccharide-Based Composite Hydrogel Sensor Integrated with Underwater Repeatable Self-Adhesion and Rapid Self-Healing for Human Motion Detection

Abstract

Tough, biocompatible, and conductive hydrogel-based strain sensors are attractive in the fields of human motion detection and wearable electronics, whereas it is still a great challenge to simultaneously integrate underwater adhesion and self-healing properties into one hydrogel sensor. Here, a highly stretchable, sensitive, and multifunctional polysaccharide-based dual-network hydrogel sensor was constructed using dialdehyde carboxymethyl cellulose (DCMC), chitosan (CS), poly(acrylic acid) (PAA), and aluminum ions (Al 3+ ). The obtained DCMC/CS/PAA (DCP) composite hydrogels exhibit robust mechanical strength and good adhesive and self-healing properties, due to the reversible dynamic chemical bonds and physical interactions such as Schiff base bonds and metal coordination. The conductivity of hydrogel is 2.6 S/m, and the sensitivity (gauge factor (GF)) is up to 15.56. Notably, the DCP hydrogel shows excellent underwater repeatable adhesion to animal tissues and good self-healing properties in water (self-healing rate > 90%, self-healing time < 10 min). The DCP hydrogel strain sensor can sensitively monitor human motion including finger bending, smiling, and wrist pulse, and it can steadily detect human movement underwater. This work is expected to provide a new strategy for the design of high-performance intelligent sensors, particularly for applications in wet and underwater environments.

Enhancing Strain-Sensing Properties of the Conductive Hydrogel by Introducing PVDF-TrFE

“…Compared with other chitosan hydrogel sensors, the GF of Pp-hydrogel has obvious advantages. Compared with the hydrogel sensor based on chitosan and its derivatives as framework (Figure e), the Pp-hydrogel also has advantages. ,,,,,− ,,− …”

“…Hydrogels are flexible materials with three-dimensional cross-linked hydrophilic polymer networks. − Conductive hydrogels combine the electrical properties of conductive materials with the flexibility and biocompatibility of hydrogels and have been widely used in flexible sensors, − wearable electronic devices, electronic skin, and other fields. In recent years, wearable sensors based on conductive hydrogels have attracted much attention.…”

Cryopolymerized Polyampholyte Gel with Antidehydration, Self-Healing, and Shape-Memory Properties for Sustainable and Tunable Sensing Electronics

“…Apart from the problem of dehydration, hydrogels are susceptible to physical damage caused by an external force, particularly in load-bearing applications. In this case, self-healing has been proposed to prolong the working lifetime and performance of a hydrogel as well as the derived wearable sensing electronics. − From the view of chemistry, incorporating noncovalent bonds and reversible covalent bonds is the mainstream for developing self-healing hydrogels . Currently, noncovalent bonds for self-healing hydrogels are hydrogen bonds, ionic bonds, π–π stacking, metal-ion binding, and other dynamic interactions. , Chen and co-workers reported a kind of hydrogel-based strain sensor that was fabricated by dialdehyde 2,2,6,6-tetramethylpiperidine-1-oxyl oxidized nanofibrillated cellulose (DATNFC) reinforced gelatin nanocomposite hydrogel (gelatin/DATNFC) which was finally dipped in Fe 3+ aqueous solution .…”

Ultra-stretchable, Antifatigue, Adhesive, and Self-Healing Hydrogels Based on the Amino Acid Derivative and Ionic Liquid for Flexible Strain Sensors

“…Other non-catechol hydrogels have been reported to overcome the above shortcomings. Several strategies for adhesive hydrogels have been developed, and the adhesion mechanisms include hydrogen bonding, 23 electrostatic interactions, 24,25 topological adhesion, 26,27 dynamic covalent interactions, 28 hydrophobic interactions, 29 metal coordination, 30 etc. On the other hand, most of the adhesive hydrogels mainly solved problems of adhesion strength and underwater adhesion, which are of great help to solve the practical application of hydrogels.…”